Telephone.



UNITED STATES PATENT OFFICE.

MILLER REESE HUTCHISON, OF NEW YORK, N. Y., ASSIGNOR, BY MESNE ASSIGNMENTS, TO HUTCHISON ACOUSTIC COMPANY, A CORPORATION OF NEW JERSEY.

TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 718,204, dated January 13, 1903. Application filed November 15,1901. Serial No. 82,481. (No model.)

T0 at whom it may concern:

Be it known that I, MILLER REESE HUTCHI SON, a citizen of the United States, residing at the city of New York, in the borough of Manhattan and State of New York, have invented certain new and useful Improvements in Telephones, of which the following is afull, clear, and exact description.

This invention relates to telephone-transmitters, the object being to provide an instrument of the type in which granular material is used between the electrodes of such construction that the said material will not become packed, as is often the casein ordinary forms of this type of instrument, and which will be very sensitive in action. In. carrying out this idea my improved transmitter consists of a diaphragm, preferably arranged horizontally and having attached at the center of one of its faces a number of conducting-plates insulated from each other and when necessary from the diaphragm, some of said plates being connected to one side of the circuit and the remainder to the other side of the circuit, the granular material, such as carbon, resting upon or in contact with all of said plates. The plates are secured to the upper side of the horizontal diaphragm, the granular material being placed in a thin layer on top of the plates and extending throughout their surface. Thus the tendency of the granular material to pack is avoided by the fact that the said material is not deep in a vertical direction and gravity can have but little influence upon it. Furthermore, since the plates are of large surface and the layer of granular material is of considerable width the on rrent is forced to traverse large portions of the granular material, and is consequently more affected by'the latter, thus rendering the instrument more sensitive.

My invention will be described in the accompanying drawings, in which Figure l is a sectional view of one form of my improved transmitter. Fig. 2 is a plan of the diaphragm shown in Fig. 1. Fig. 3 is a plan of the diaphragm, showing a modified form of electrodes; and Fig. 4 is a sectional View of the construction shown in Fig. 3.

A indicates the frame or case of the transmitter. This I preferably support in a horizontal position, as shown, fixing it to a desk or other support in such a way that it cannot be tipped at an angle. The diaphragm is indicated by B, and it is clamped in the easing between the cap and rear portions, as shown. At the center of the diaphragm and on its upper side are secured a number of conducting-plates a a, and b b. As shown in Fig. 2, these plates are sectors of circles placed with their apexes toward the center and separated from each other by insulating material 0, which is leveled off to form a smooth even surface extending over all of the plates and the insulation. When the diaphragm is of non-conducting material, the plates may be secured directly thereto, but when a diaphragm of conducting material is used the plates should be secured by means of a nonconducting cement, so that they will be efiectually insulated from each other. On the upper smooth surface of the plates I place a thin layer of any suitable granulated material, (indicated by c.) This maybe confined within a band of textile material commonly used in transmitters and which may encircle the outer edge of the plates, or it might be confined by a coverf, having a flange passing tightly down over the edges of the plates, as shown in Fig. 1. In the form shown in Fig. 3 the plates Ct, a, and b are rings concentrically placed,with the space between them filled with insulating material. This construction will also have a smooth upper surface, upon which will be placed a layer of granular 1naterial,which will be confined at the edges by means of the textile band g, as shown in Fig. 4, and at the top bya plate It, of'non-conducting material.

Where an even number of plates are used,

,as in Fig. 2, one half of the number is to be are connected together by the wire 3 and I00 then to the line, while the third is connected directly with the other line. It is therefore obvious that various numbers of these plates can be used, and it may be stated in general that the greater the number of plates the more distinct will be the talking.

\Vhen a horizontal diaphragm is used, the mouthpiece for conducting the sound to the diaphragm may be fixed to the top or to the bottom of the box, as desired; but I have shown a mouthpiece 0 leading to the under side of the diaphragm and curving laterally to present the opening at a convenient position to be spoken into.

I also wish to point out that while I have shown and prefer a horizontal instrument good results can nevertheless be obtained by using the instrument. in an angular or vertical position, for it is evident that a large part of the sensitiveness will remain even when the instrument is placed at an angle.

It is not essential that the plates and granular material should be located on the upper side of the diaphragm, as when proper means are provided for preventing the escape of the granular material, such as shown in Fig. 1, it may be located on the under side of the diaphragm, the only essential point being that the layer of granular material shall be held in contact with the plates. The upper side of the diaphragm is, however, preferred for these parts.

Having described my invention, I claim- In a telephone-transmitter, the combination of adiaphragm, a set of conductingplates arranged in succession around the center thereof, each alternate plate being connected with one side of the transmittercircuit While the other plates are connected to the other side, and alayer of granular material covering the surface of said plates, substantially as described.

In witness whereof I subscribe my signature in presence of two witnesses.

MILLER REESE HUTGI'IISON. Witnesses:

FRANK S. OBER, WALDO M. CHAPIN. 

